This invention relates generally to gas turbine engines and more particularly to the cleaning of gas turbine engines.
Gas turbine engines are generally required to be tested prior to final delivery to the intended customer. Prior to or during testing of the engine, it may be desirable to remove any fuel or oil residue on engine components to permit identification of any leaks that may occur during test operations. After a leak is identified and repaired, it is desirable to remove any remaining fuel and oil residue prior to shipment to the customer.
One approach to cleaning engines involves using an HCFC (hydrochlorofluorocarbon) composition, such as HCFC 141b. Another approach involves using isopropyl alcohol as a cleaning agent. Still other approaches include using steam, aqueous cleaners, hydrofluoroethers alone or mixed with other substances such as isopropyl alcohol or n-propyl bromide.
One challenge in identifying an acceptable cleaner is that the cleaner should be effective and quick acting, while meeting requirements related to environmental and safety regulations. Such requirements can include flammability, worker exposure limitations, and air and water pollution standards. For instance, the cleaning composition should be nonflammable in use on hot engine surfaces. Additionally, it is desirable to provide an effective cleaning composition which is non-ozone depleting and has a low global warming potential. Water and detergent cleaning compositions have been proposed to provide cleaning effectiveness while meeting safety and environmental requirements. However, such water based compositions have the disadvantage that water does not evaporate quickly, and water based compositions may enter electrical/electronic components on the engine, especially if the water is sprayed under pressure.
Accordingly, it would be desirable to provide a composition and method for cleaning gas turbine engines with improved effectiveness and which also meets requirements related to environmental and safety issues, and which does not pose a potential threat to electrical/electronic components of the gas turbine engine.
The present invention provides a composition and method for cleaning hydrocarbon residue, such as fuel or lubricant residue, from one or more components of a gas turbine engine, including hot surfaces of a gas turbine engine. The composition comprises a fluorine-containing first constituent and a flourine-containing second constituent which is an effective solvent. The first constituent can comprise one or more hydrofluoroethers. The second constituent comprises one or more hydrofluorocarbons. In one embodiment, the composition can comprise less than 75% by volume of each of the hydrofluoroether and the hydrofluorocarbon, and the hydrofluorocarbon content is less than that of the hydrofluoroether. The cleaning composition can include about 40% by volume of Dupont VERTREL XF brand hydrofluorocarbon and about 60% by volume of 3M HFE-7100 NOVEC brand hydrofluoroether.
The present invention also provides a method of cleaning gas turbine engines having a residue, such as fuel or lubricant residue. The method can include the steps of providing a gas turbine engine having a hydrocarbon residue on at least a portion of the gas turbine engine, and applying the cleaning composition to remove the residue. In one embodiment, the cleaning solution is directed in a pressurized stream to remove residue from the gas turbine engine. The cleaning solution can be applied to the gas turbine engine prior to running the gas turbine engine, and/or can be applied to a hot surface of a gas turbine engine during operation of the gas turbine engine. For instance, the cleaning solution can be used to clean fluid conduit components, such as tubing, tubing connections, and tubing fittings, and accessory components such as valves, pumps, gearboxes, and the like.